The expected duration of this study for each participant is 21 days. Study participants will be randomly assigned to one of two arms. Participants in Arm 1 will apply 3.5 g of SPL7013 gel intravaginally twice daily for 14 consecutive days. Participants in Arm 2 will apply a placebo gel intravaginally twice daily for 14 consecutive days. Starpharma produces SPL7013 gel (VivaGel) and will provide it for this study.